The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Oncorhynchus mykiss
Oncorhynchus mykiss
(Rainbow Trout)
Native Transplant

Copyright Info
Oncorhynchus mykiss (Walbaum, 1792)

Common name: Rainbow Trout

Synonyms and Other Names: steelhead [anadromous form], coastal rainbow

Taxonomy: available through www.itis.govITIS logo

Identification: Rainbow trout are a deep-bodied, compressed species with a typical trout body shape, a moderately large head, and a mouth that extends back behind the eyes. Rainbow trout have highly variable coloration: those that live in lakes are silvery with a dark olive-green colour on the back, though the dorsal coloration is sometimes a deep steely blue, mostly in fish that live offshore in deep lakes or in small fish that have not yet spawned. Numerous spots are present on the back and extend about two-thirds of the way to the lateral line down the sides. The sides are silvery and largely free of spots, the belly and ventral surface of the head are whitish, and sometimes a soft metallic-pink color is present along the sides of the body and the head (GISD, 2019).

When rainbow trout leave lakes to spawn, their coloration becomes more intense: the pinkish stripe that is present on the sides of lake fish, along with the fins, turn a rich crimson color, and there is sometimes a red slash in the folds below the lower jaw. The belly and the lower sides turn gray, and spots on the sides and upper fins become bolder and more clearly delineated. Juvenile trout are olive-green along their back and silvery olive high on their sides. There are 8-13 oval-shaped marks along the sides, which may also have smaller dark spots along them. Blush-pink to yellowish markings occur along the lateral lines between the oval marks (McDowall, 1990).

For further identification guides, see Moyle (1976a); Scott and Crossman (1973); Wydoski and Whitney (1979); Morrow (1980); Eschmeyer et al. (1983); Page and Burr (1991); Behnke (1992). Behnke (1992) gave accounts and drawings for several subspecies. A commonly used named for this species is Salmo gairdnerii, sometimes given as S. gairdneri.

Size: 114 cm

Native Range: Pacific Slope from Kuskokwim River, Alaska, to (at least) Rio Santa Domingo, Baja California; upper Mackenzie River drainage (Arctic basin), Alberta and British Columbia; endorheic basins of southern Oregon (Page and Burr 1991).

Native range data for this species provided in part by NatureServe NS logo
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Oncorhynchus mykiss are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AL196220018Guntersville Lake; Locust; Middle Tennessee-Elk; Mobile Bay; Mobile-Tombigbee; Pickwick Lake; Sipsey Fork; Upper Tallapoosa
AK195219804Chena River; Healy Lake-Tanana River; Middle Copper River; Tanana Flats-Tanana River
AZ1880201433Agua Fria; Bill Williams; Black; Canyon Diablo; Chevelon Canyon; Detrital Wash; Grand Canyon; Havasu Canyon; Havasu-Mohave Lakes; Lake Mead; Little Colorado Headwaters; Lower Colorado Region; Lower Colorado-Marble Canyon; Lower Lake Powell; Lower Little Colorado; Lower Salt; Lower Verde; Lower Virgin; Middle Gila; Middle Little Colorado; Paria; Rillito; San Francisco; Santa Maria; Silver; Tonto; Upper Gila-San Carlos Reservoir; Upper Little Colorado; Upper Salt; Upper Santa Cruz; Upper Verde; Whitewater Draw; Willcox Playa
AR1950201817Beaver Reservoir; Bull Shoals Lake; Dardanelle Reservoir; Elk; Illinois; Lake Conway-Point Remove; Little Missouri; Little Red; Lower Neosho; Lower White; Middle White; North Fork White; Ouachita Headwaters; Robert S. Kerr Reservoir; Spring; Strawberry; Upper Ouachita
CA1930202049Antelope-Fremont Valleys; Clear Creek-Sacramento River; Cottonwood-Tijuana; Coyote; Crowley Lake; Death Valley-Lower Amargosa; East Branch North Fork Feather; East Walker; Imperial Reservoir; Lake Tahoe; Lower Klamath; Lower Pit; McCloud; Middle Fork Feather; Newport Bay; North Fork American; North Fork Feather; Pajaro; Sacramento Headwaters; Salmon; San Diego; San Pablo Bay; Santa Barbara Coastal; Santa Clara; Santa Margarita; Santa Monica Bay; Scott; South Fork American; South Fork Kern; Suisun Bay; Surprise Valley; Tomales-Drake Bays; Trinity; Truckee; Upper Bear; Upper Cache; Upper Carson; Upper Cosumnes; Upper Kern; Upper King; Upper Mokelumne; Upper Putah; Upper Stanislaus; Upper Stony; Upper Tuolumne; Upper Yuba; Ventura; Warner Lakes; West Walker
CO1880202447Alamosa-Trinchera; Animas; Arkansas Headwaters; Big Thompson; Blue; Cache La Poudre; Clear; Colorado Headwaters; Colorado Headwaters-Plateau; Conejos; Eagle; East-Taylor; Fountain; Gunnison; Huerfano; Lower Green-Diamond; Lower Gunnison; Lower Yampa; Middle South Platte-Cherry Creek; Middle South Platte-Sterling; North Platte; North Platte Headwaters; Piedra; Purgatoire; Republican; Rio Grande Headwaters; Roaring Fork; San Luis; San Miguel; South Fork Republican; South Platte; South Platte Headwaters; St. Vrain; Tomichi; Uncompahgre; Upper Arkansas; Upper Arkansas-Lake Meredith; Upper Dolores; Upper Green-Flaming Gorge Reservoir; Upper Gunnison; Upper Laramie; Upper North Platte; Upper San Juan; Upper South Platte; Upper White; Upper Yampa; White - Yampa
CT187520207Farmington River; Housatonic; New England Region; Outlet Connecticut River; Pawcatuck River; Saugatuck; Thames
DE188820204Brandywine-Christina; Broadkill-Smyrna; Delaware Bay; Mid Atlantic Region
FL196819681Choctawhatchee Bay
GA1962202116Apalachicola Basin; Conasauga; Etowah; Hiwassee; Little; Middle Chattahoochee-Lake Harding; Middle Savannah; Middle Tennessee-Chickamauga; Ocoee; Oostanaula; Savannah; South Atlantic-Gulf Region; Tugaloo; Upper Chattahoochee; Upper Oconee; Upper Savannah
HI192020053Hawaii; Kauai; Oahu
ID1941202272American Falls; Bear Lake; Beaver-Camas; Big Lost; Big Wood; Birch; Blackfoot; Boise-Mores; Brownlee Reservoir; Bruneau; C.J. Strike Reservoir; Camas; Clearwater; Coeur d'Alene Lake; Curlew Valley; Goose; Hangman; Hells Canyon; Idaho Falls; Lake Walcott; Lemhi; Little Lost; Little Salmon; Little Wood; Lochsa; Lower Bear-Malad; Lower Boise; Lower Clark Fork; Lower Henrys; Lower Kootenai; Lower Middle Fork Salmon; Lower North Fork Clearwater; Lower Salmon; Lower Selway; Lower Snake-Asotin; Middle Bear; Middle Fork Payette; Middle Kootenai; Middle Salmon-Chamberlain; Middle Salmon-Panther; Middle Snake-Succor; Moyie; North and Middle Forks Boise; North Fork Payette; Pahsimeroi; Palisades; Payette; Pend Oreille; Pend Oreille Lake; Portneuf; Priest; Raft; Salmon Falls; South Fork Boise; South Fork Clearwater; South Fork Coeur d'Alene; South Fork Payette; South Fork Salmon; Spokane; St. Joe; Teton; Upper Coeur d'Alene; Upper Henrys; Upper Middle Fork Salmon; Upper North Fork Clearwater; Upper Owyhee; Upper Salmon; Upper Selway; Upper Snake-Rock; Upper Spokane; Weiser; Willow
IL1959202317Big Muddy; Copperas-Duck; Des Plaines; Embarras; Green; Lake Michigan; Little Calumet-Galien; Lower Fox; Lower Illinois; Lower Illinois-Lake Chautauqua; Lower Rock; Pike-Root; Rock; Upper Illinois; Upper Illinois; Upper Mississippi; Upper Mississippi Region
IN1901199911Blue-Sinking; Kankakee; Lake Michigan; Little Calumet-Galien; Ohio Region; Patoka; Patoka-White; St. Joseph; Sugar; Tippecanoe; Wabash
IA1979200110Apple-Plum; Coon-Yellow; Grant-Little Maquoketa; Lower Iowa; Maquoketa; Middle Cedar; Turkey; Upper Cedar; Upper Iowa; Upper Wapsipinicon
KS196720196Arkansas-White-Red Region; Medicine Lodge; Missouri Region; Neosho-Verdigris; Smoky Hill Headwaters; Upper Kansas
KY1972202422Barren; Blue-Sinking; Kentucky; Licking; Little Sandy; Little Scioto-Tygarts; Lower Cumberland; Lower Green; Lower Kentucky; Lower Levisa; Middle Fork Kentucky; Ohio Brush-Whiteoak; Red; Rockcastle; Rough; South Fork Cumberland; South Fork Licking; Upper Cumberland; Upper Cumberland-Lake Cumberland; Upper Green; Upper Kentucky; Upper Levisa
LA199120082Amite; East Central Louisiana Coastal
ME1914201115Androscoggin; Aroostook River; Dead River; Kennebec; Lower Androscoggin River; Lower Kennebec River; Maine Coastal; Meduxnekeag River; New England Region; Piscataqua-Salmon Falls; Piscataquis River; Presumpscot; Saco River; St. George-Sheepscot; Upper Kennebec River
MD1875202314Cacapon-Town; Chester-Sassafras; Conococheague-Opequon; Gunpowder-Patapsco; Lower Susquehanna; Mid Atlantic Region; Middle Potomac-Anacostia-Occoquan; Middle Potomac-Catoctin; Monocacy; North Branch Potomac; Patuxent; Pokomoke-Western Lower Delmarva; Severn; Youghiogheny
MA1932202018Ashuelot River-Connecticut River; Blackstone River; Cape Cod; Charles; Chicopee River; Concord River; Deerfield River; Farmington River; Housatonic; Lower Connecticut; Merrimack River; Millers River; Narragansett; Nashua River; Outlet Connecticut River; Quinebaug River; Westfield River; Winnipesaukee River
MI1876202321Au Gres-Rifle; Au Sable; Betsie-Platte; Betsy-Chocolay; Black-Presque Isle; Boardman-Charlevoix; Brule; Clinton; Dead-Kelsey; Fishdam-Sturgeon; Great Lakes Region; Lake Huron; Lake Michigan; Lake St. Clair; Lake Superior; Lower Grand; Manistee; Menominee; Pere Marquette-White; St. Clair; St. Joseph
MN1888201144Baptism-Brule; Beartrap-Nemadji; Beaver-Lester; Big Fork; Buffalo-Whitewater; Cannon; Clearwater; Clearwater-Elk; Cloquet; Coon-Yellow; Crow Wing; Des Moines Headwaters; Eastern Wild Rice; Elk-Nokasippi; Hawk-Yellow Medicine; Kettle; Lake Superior; Leech Lake; Little Fork; Lower Minnesota; Lower Rainy; Lower St. Croix; Middle Minnesota; Minnesota; Mississippi Headwaters; Otter Tail; Pine; Platte-Spunk; Prairie-Willow; Rainy; Rainy Headwaters; Red; Red Lakes; Redwood; Root; Rush-Vermillion; Sauk; South Fork Crow; St. Croix; St. Louis; Twin Cities; Upper Mississippi-Crow-Rum; Upper St. Croix; Zumbro
MS199120012Lower Mississippi-Helena; Upper Yazoo
MO188220199Bull Shoals Lake; Cahokia-Joachim; Current; Eleven Point; Harry S. Truman Reservoir; Lake of the Ozarks; Lower Gasconade; Meramec; Spring
MT1889201987Arrow; Battle; Beaver; Beaverhead; Belly; Belt; Big Dry; Big Hole; Big Horn Lake; Big Muddy; Big Porcupine; Big Sandy; Bitterroot; Blackfoot; Boulder; Box Elder; Boxelder; Bullwhacker-Dog; Charlie-Little Muddy; Clarks Fork Yellowstone; Cottonwood; Elk; Fisher; Flathead Lake; Flatwillow; Flint-Rock; Fort Peck Reservoir; Gallatin; Jefferson; Judith; Little Dry; Little Powder; Lodge; Lower Bighorn; Lower Clark Fork; Lower Flathead; Lower Milk; Lower Musselshell; Lower Powder; Lower Tongue; Lower Yellowstone; Lower Yellowstone-Sunday; Madison; Marias; Marias; Middle Clark Fork; Middle Fork Flathead; Middle Kootenai; Middle Milk; Middle Musselshell; Milk; Mizpah; Musselshell; North Fork Flathead; O'Fallon; Peoples; Poplar; Prairie Elk-Wolf; Red Rock; Rock; Ruby; Sage; Saskatchewan; Shields; Smith; South Fork Flathead; St. Marys; Stillwater; Stillwater; Sun; Swan; Teton; Tongue; Two Medicine; Upper Clark Fork; Upper Little Missouri; Upper Milk; Upper Missouri; Upper Missouri; Upper Missouri-Dearborn; Upper Musselshell; Upper Tongue; Upper Yellowstone; Upper Yellowstone-Lake Basin; Upper Yellowstone-Pompeys Pillar; Whitewater; Yellowstone Headwaters
NE1974202011Hat; Lower Lodgepole; Lower North Platte; Lower Platte; Lower South Platte; Lower Yellowstone; Middle North Platte-Scotts Bluff; Middle Platte-Buffalo; Missouri Region; North Fork Republican; Upper White
NV1880202235Bruneau; Carson Desert; Central Lahontan; Diamond-Monitor Valleys; Fish Lake-Soda Spring Valleys; Hamlin-Snake Valleys; Havasu-Mohave Lakes; Imperial Reservoir; Ivanpah-Pahrump Valleys; Lake Mead; Lake Tahoe; Little Humboldt; Long-Ruby Valleys; Lower Humboldt; Lower Virgin; Meadow Valley Wash; Middle Carson; Muddy; North Fork Humboldt; Pilot-Thousand Springs, Nevada, Utah; Pyramid-Winnemucca Lakes; Salmon Falls; Smoke Creek Desert; South Fork Humboldt; South Fork Owyhee; Southern Big Smoky Valley; Spring-Steptoe Valleys; Thousand-Virgin; Truckee; Upper Carson; Upper Humboldt; Upper Owyhee; Walker Lake; West Walker; White
NH1864202017Ammonoosuc River-Connecticut River; Ashuelot River-Connecticut River; Black River-Connecticut River; Contoocook River; Headwaters Connecticut River; Lower Androscoggin River; Merrimack River; Millers River; Nashua River; New England; Pemigewasset River; Piscataqua-Salmon Falls; Saco River; Upper Androscoggin River; Waits River-Connecticut River; West River-Connecticut River; Winnipesaukee River
NJ195220238Cohansey-Maurice; Hackensack-Passaic; Lower Delaware; Mid-Atlantic Region; Middle Delaware-Mongaup-Brodhead; Middle Delaware-Musconetcong; Raritan; Sandy Hook-Staten Island
NM1957202125Animas; Canadian Headwaters; Carrizo Wash; Cimarron; Conejos; Jemez; Middle San Juan; Mimbres; Pecos Headwaters; Rio Chama; Rio Grande-Albuquerque; Rio Grande-Santa Fe; Rio Hondo; San Francisco; Tularosa Valley; Upper Beaver; Upper Canadian; Upper Canadian; Upper Gila; Upper Gila-Mangas; Upper Pecos; Upper Rio Grande; Upper San Juan; Upper San Juan; Zuni
NY1874202026Ausable River; Black; Cattaraugus; Chenango; Hudson-Hoosic; Lake Champlain; Lake Ontario; Long Island; Lower Genesee; Lower Hudson; Mettawee River; Middle Hudson; Mohawk; Owego-Wappasening; Raisin River-St. Lawrence River; Raquette; Sacandaga; Sandy Hook-Staten Island; Saranac River; Schoharie; Seneca; St. Regis; Upper Delaware; Upper Hudson; Upper Susquehanna; Upper Susquehanna
NC1903202219French Broad-Holston; Hiwassee; Lower Little Tennessee; Lower Yadkin; Nolichucky; Pigeon; Roanoke; Seneca; South Fork Catawba; Tuckasegee; Upper Broad; Upper Catawba; Upper French Broad; Upper Little Tennessee; Upper New; Upper Pee Dee; Upper Tennessee; Upper Yadkin; Watauga, North Carolina, Tennessee
ND198019963Lake Sakakawea; Painted Woods-Square Butte; Red
OH1885202322Ashtabula-Chagrin; Black-Rocky; Chautauqua-Conneaut; Cuyahoga; Grand; Hocking; Huron-Vermilion; Lake Erie; Little Miami; Little Muskingum-Middle Island; Lower Great Miami, Indiana, Ohio; Lower Scioto; Muskingum; Ohio Brush-Whiteoak; Paint; Sandusky; Tuscarawas; Upper Great Miami, Indiana, Ohio; Upper Ohio-Shade; Upper Ohio-Wheeling; Upper Scioto; Walhonding
OK196120217Arkansas-White-Red Region; Blue; Cache; Illinois; Lower Verdigris; Polecat-Snake; Upper Cimarron
OR1928200310Brownlee Reservoir; Clackamas; Lower Crooked; Lower Grande Ronde; Lower Malheur; Middle Owyhee; North Umpqua; Pacific Northwest Region; Upper Malheur; Willow
PA1983202011Allegheny; Chautauqua-Conneaut; Conococheague-Opequon; Lake Erie; Lehigh; Lower Allegheny; Lower Monongahela; Middle Delaware-Mongaup-Brodhead; Shenango; Susquehanna; Upper Ohio
PR193419424Cibuco-Guajataca; Culebrinas-Guanajibo; Eastern Puerto Rico; Puerto Rico
SC1971202010Congaree; Cooper; Enoree; Middle Savannah; Saluda; Santee; Santee; Seneca; Tugaloo; Upper Savannah
SD1950202316Big Sioux; Cheyenne; Fort Randall Reservoir; Grand; James; Lewis and Clark Lake; Lower Belle Fourche; Lower James; Lower Lake Oahe; Middle Big Sioux; Middle Cheyenne-Spring; Missouri Region; Rapid; Redwater; Upper Moreau; Vermillion
TN1939202325Buffalo; Caney; Collins; Conasauga; Emory; Hiwassee; Lower Clinch; Lower Cumberland; Lower Cumberland-Sycamore; Lower Duck; Lower French Broad; Lower Little Tennessee; Middle Tennessee-Elk; Middle Tennessee-Hiwassee; Obey; Ocoee; South Fork Holston; Upper Clinch, Tennessee, Virginia; Upper Cumberland; Upper Elk; Upper French Broad; Upper Tennessee; Watauga, North Carolina, Tennessee; Watts Bar Lake; Wheeler Lake
TX1892202268Austin-Travis Lakes; Bois D'arc-Island; Buchanan-Lyndon B. Johnson Lakes; Buffalo-San Jacinto; Cedar; Cibolo; East Fork San Jacinto; East Fork Trinity; Elm Fork Trinity; International Falcon Reservoir; Johnson Draw; Lake Meredith; Lake O'the Pines; Lampasas; Landreth-Monument Draws; Leon; Little Cypress; Lower Brazos; Lower Brazos; Lower Colorado-Cummins; Lower Frio; Lower Guadalupe; Lower Neches; Lower Nueces; Lower Prairie Dog Town Fork Red; Lower Sabine; Lower Sulpher; Lower West Fork Trinity; Maravillas; Middle Brazos-Lake Whitney; Middle Brazos-Palo Pinto; Middle Canadian-Spring; Middle Guadalupe; Middle Sabine; Navasota; Navidad; North Bosque; North Concho; North Fork Double Mountain Fork Brazos; North Laguna Madre; Pease; Pedernales; Richland; Rio Grande-Falcon; Rio Grande-Fort Quitman; San Gabriel; San Marcos; San Saba; South Concho; South Corpus Christi Bay; South Laguna Madre; South Llano; Texas-Gulf Region; Tierra Blanca; Tule; Upper Clear Fork Brazos; Upper Guadalupe; Upper Neches; Upper Pecos-Black; Upper Prairie Dog Town Fork Red; Upper Sabine; Upper Salt Fork Red; Upper San Antonio; Upper Trinity; Upper West Fork Trinity; West Fork San Jacinto; West Galveston Bay; Wichita
UT1880202337Bear Lake; Beaver Bottoms-Upper Beaver; Blacks Fork; Duchesne; East Fork Sevier; Escalante; Escalante Desert; Fremont; Jordan; Little Bear-Logan; Lower Bear-Malad; Lower Green; Lower Green-Desolation Canyon; Lower Green-Diamond; Lower Lake Powell; Lower San Juan-Four Corners; Lower Sevier; Lower Weber; Middle Bear; Middle Sevier; Montezuma; Price; Provo; Rush-Tooele Valleys; San Pitch; San Rafael; Spanish Fork; Strawberry; Upper Bear; Upper Colorado-Dirty Devil; Upper Colorado-Kane Springs; Upper Green-Flaming Gorge Reservoir; Upper Lake Powell; Upper Sevier; Upper Virgin; Upper Weber; Utah Lake
VT1980202018Ammonoosuc River-Connecticut River; Black River-Connecticut River; Deerfield River; Headwaters Connecticut River; Hudson-Hoosic; Lake Champlain; Lamoille River; Mettawee River; Missiquoi River; Otter Creek; Passumpsic River; Richelieu; St. Francois; St. Francois River; Waits River-Connecticut River; West River-Connecticut River; White River; Winooski River
VA1945202428Conococheague-Opequon; James; Kanawha; Lower James; Lower Potomac; Lower Rappahannock; Maury; Middle James-Buffalo; Middle New; Middle Roanoke; North Fork Holston; North Fork Shenandoah; Potomac; Powell; Rapidan-Upper Rappahannock; Rivanna; Roanoke; Shenandoah; South Branch Potomac; South Fork Holston; South Fork Shenandoah; Upper Clinch, Tennessee, Virginia; Upper Dan; Upper James; Upper Levisa; Upper New; Upper Roanoke; Upper Yadkin
WA192020053Franklin D. Roosevelt Lake; Middle Columbia-Lake Wallula; Pacific Northwest Region
WV1986202211Big Sandy; Guyandotte; James; Kanawha; Little Kanawha; Little Muskingum-Middle Island; Middle New; Monongahela; Potomac; Upper James; Upper Kanawha
WI1888202349Apple-Plum; Bad-Montreal; Baraboo; Beartrap-Nemadji; Black; Black-Presque Isle; Brule; Buffalo-Whitewater; Castle Rock; Coon-Yellow; Door-Kewaunee; Duck-Pensaukee; Eau Claire; Flambeau; Grant-Little Maquoketa; Great Lakes Region; Jump; Kickapoo; La Crosse-Pine; Lake Dubay; Lake Michigan; Lake Superior; Lower Chippewa; Lower Fox; Lower St. Croix; Lower Wisconsin; Manitowoc-Sheboygan; Menominee; Middle Rock; Milwaukee; Namekagon; Oconto; Ontonagon; Pecatonica; Peshtigo; Pike-Root; Red Cedar; Rush-Vermillion; South Fork Flambeau; St. Louis; Sugar; Trempealeau; Upper Chippewa; Upper Fox; Upper Fox; Upper Rock; Upper St. Croix; Upper Wisconsin; Wolf
WY1880202323Big Horn; Blacks Fork; Cheyenne; Crazy Woman; Crow; Great Divide Closed Basin; Gros Ventre; Missouri Headwaters; North Fork Shoshone; North Platte; Pathfinder-Seminoe Reservoirs; Snake Headwaters; South Platte; Upper Bighorn; Upper Green; Upper Green; Upper Green-Flaming Gorge Reservoir; Upper Green-Slate; Upper North Platte; Upper Wind; Upper Yellowstone; White - Yampa; Yellowstone Headwaters

Table last updated 6/14/2024

† Populations may not be currently present.

Ecology: Lake fish usually spawn in lake tributaries, where the young trout feed and grow before migrating downstream after about a year. Growing to maturity in the lake takes between 2-4 years, at which time they migrate back to the tributaries to spawn. Most fish will return to the tributary in which they hatched (McDowall, 1990). Some lake populations may spawn in lake-shore gravels rather than travel into tributaries, however. Adult rainbow trout eat insects (both aquatic and terrestrial), crustaceans, molluscs, fish eggs, and small fish. Young trout feed predominantly on zooplankton (GISD, 2019).

Means of Introduction: Beginning in the late 1800s, there have been many stockings of this species for sportfishing purposes by state and federal agencies and by private individuals, mostly into streams and spring branches. Some states stock on an annual basis.

Status: Established in many states, including Hawaii. Also frequently stocked in most states to replenish populations harvested by fishing pressures or in other areas where populations are not self sustaining. One specimen collected from Mississippi (Ross and Brenneman 1991). Stocked once, in 1991, in Louisiana. The stocking failed. Previously established in Soda Butte Creek in Yellowstone National Park. Extirpated via rotenone treatments in 2015 and 2016; currently monitoring and eDNA testing (Ertel 2018).

Impact of Introduction: The rainbow trout hybridizes with other, more rare trout species, thereby affecting their genetic integrity (Lee et al. 1980 et seq.; Rinne and Minckley 1985; Page and Burr 1991). In California, rainbow trout have hybridized with Lahontan cutthroat trout O. clarki henshawi, golden trout O. aguabonita, and redband trout O. mykiss subsp. to the point that all three are included in the threatened trout management program of the California Department of Fish and Game (McAffee 1966b; Moyle 1976b; Behnke 1992). In the Lahontan drainage and various Rocky Mountain rivers, hybridization with rainbow trout has been a major factor in the decline of native cutthroat trouts (McAffee 1966a). Rainbow trout have been shown to hybridize with Westslope cutthroat trout throughout the Flathead River system in Montana (Muhlfeld et. al, 2009). In Nevada, this species is also held responsible for the virtual extinction of Alvord cutthroat O. mykiss subsp. (Behnke 1992). In Arizona, the species has hybridized with native gila trout O. gilae and Apache trout O. apache (Minckley 1973; U.S. Fish and Wildlife Service 1979). Rainbow trout have replaced Lahontan cutthroat trout in areas where the cutthroat is native and Rainbow Trout have been introduced (McAffee 1966b). Introduced rainbow trout, and other trout species, were likely responsible for the near-extinction of Lahontan cutthroat in Lake Tahoe in the 1940s (McAffee 1966b). Oncorhynchus clarkii lewisi hybridization with O. mykiss, and the resulting backcrossing to pure parent populations, has resulted in strong introgression toward both populations in the Upper Oldman River, Alberta, Canada (Rasmussen et al. 2010).

Rainbow trout have been found to negatively affect Little Colorado spinedace Lepidomeda vittata through predation and by affecting spinedace behavior. The trout occupied undercut banks that the spinedace normally used for refuge. As a result, spinedace were displaced from preferred microhabitats and pushed into open water, making them vulnerable to predation (Blinn et al. 1993). Thibault and Dodsen (2013) found significant habitat niche overlap between introduced Rainbow Trout and two native salmonids, Atlantic salmon Salmo salar and brook trout Salvelinus fontinatlis, within eastern Quebec rivers, and increased habitat overlap between native salmonids in rivers containing rainbow trout.

Stocking of hatchery rainbow trout in rivers has led to introduction of whirling disease into open waters in approximately 20 states including, most recently, the Madison River and its tributaries in Montana (B. Nehring and R. White, personal communication). In the Madison River, the disease has reduced the rainbow trout population by 90% (White, personal communication). Rainbow trout have the potential to consume native fishes and compete with native salmonids (Page and Laird 1993). Introduced rainbow trout eat endangered humpback chub Gila cypha in the Little Colorado River, and may exert a major negative effect on the population there (Marsh and Douglas 1997). Fausch (1988), Clark and Rose (1997), and numerous papers cited in both, discussed several factors affecting competitive interactions between rainbow and brook trout. Rainbow trout drive nongame fishes such as suckers and squawfish from feeding territories (Li, personal communication to P. Moyle in Moyle 1976a). Introduced predatory fishes, including the rainbow trout, are likely at least partially responsible for the decline of the Chiricahua leopard frog Rana chiricahuensis in southeastern Arizona (Rosen et al. 1995).

Remarks: Tyus et al. (1982) mapped the distribution of rainbow trout in the upper Colorado basin.

References: (click for full references)

Anonymous. 2000. Northwestern Pa. waters. James's Northeastern Fishing Guide.

Behnke, R.J. 1992. Native trout of western North America. American Fisheries Society Monograph 6. American Fisheries Society, Bethesda, MD, 275 pp.

Blinn, D.W., C. Runck, D.A. Clark, and J.N. Rinne. 1993. Effects of rainbow trout predation on Little Colorado spinedace. Transactions of the American Fisheries Society 122:139-143.

Boogaard, M.A., T.D. Bills, and D.A. Johnson. 2003. Acute toxicity of TFM and a TFM/niclosamide mixture to selected species of fish, including lake sturgeon (Acipenser fulvescens) and Mudpuppies (Necturus maculosus), in Laboratory and Field Exposures. Journal of Great Lakes Research 29(Supplement 1):529-541.

Bradley, W.G., and J.E. Deacon. 1967. The biotic communities of southern Nevada. Nevada State Museum Anthropological Papers No. 13, Part 4. 201-273.

Burkhead, N.M., S.J. Walsh, B.J. Freeman, and J.D. Williams. 1997. Status and restoration of the Etowah River, an imperiled southern Appalachian ecosystem, p 375-444, In: G.W. Benz and D.E. Collins (eds). Aquatic Fauna in Perile: The Southeastern Perspective. Special Publication 1, Southeast Aquatic Research Institute, Lenz Design & Communications, Decatur, GA.

Champion, P., J. Clayton, and D. Rowe. 2002. Lake Manager's Handbook: Alien Invaders. New Zealand Ministry for the Environment, Wellington, New Zealand.

Clark, M.E., and K.A. Rose. 1997. Factors affecting competitive dominance of rainbow trout over brook trout in southern Appalachian streams: implications of an individual-based model. Transactions of the American Fisheries Society 126(2):1-20.

Clearwater, S.J., C.W. Hickey, and M.L. Martin. 2008. Overview of potential piscicides and molluscicides for controlling aquatic pest species in New Zealand. Science & Technical Publishing, New Zealand Department of Conservation, Wellington, New Zealand.

Courtenay, W.R., Jr., and J.R. Stauffer, Jr., eds. Distribution, Biology, and Management of Exotic Fishes. John Hopkins. Baltimore and London.

Crawford, S.S. 2001. Salmonine introductions to the Laurentian Great Lakes: an historical review and evaluation of ecological effects. Canadian Special Publication of Fisheries and Aquatic Sciences No. 132. 205 pp.

Cudmore-Vokey, B., and E.J. Crossman. 2000. Checklists of the fish fauna of the Laurentian Great Lakes and their connecting channels. Canadian Manuscript Report of Fisheries and Aquatic Sciences 2500: v + 39 pp.

Ertel, B. 2018. Preservation of Native Cutthroat Trout in Northern Yellowstone. https://www.nps.gov/articles/preservation-of-native-cutthroat-trout-in-northern-yellowstone.htm. Accessed on 04/23/2018.

Fausch, K.D. 1988. Tests of competition between native and introduced salmonids in streams: what have we learned? Canadian Journal of Fisheries and Aquatic Sciences 45(12):2238-2246.

Feltmate, B.W., and D.D. Williams. 1989. Influence of rainbow trout (Oncorhynchus mykiss) on density and feeding behavior of a perlid stonefly. Canadian Journal of Fisheries and Aquatic Sciences 46(9):1575-1580.

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Other Resources:
Distribution in Illinois - Illinois Natural History Survey

Oncorhyncus mykiss - Global Invasive Species Database

Great Lakes Waterlife

FishBase Summary

Author: Fuller, P., J. Larson, A. Fusaro, T.H. Makled, and M. Neilson

Revision Date: 9/12/2019

Peer Review Date: 11/4/2013

Citation Information:
Fuller, P., J. Larson, A. Fusaro, T.H. Makled, and M. Neilson, 2024, Oncorhynchus mykiss (Walbaum, 1792): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=910, Revision Date: 9/12/2019, Peer Review Date: 11/4/2013, Access Date: 6/14/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/14/2024].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted.

For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.